CN104128193A - CeO2 based SCR catalyst and preparation method thereof - Google Patents

Abstract

The invention discloses a CeO2 based SCR catalyst and a preparation method thereof. The preparation method comprises the following steps: taking a proper amount of a metal oxide powder containing CeO2 or a metal salt solution including soluble salt of Ce; soluble salts; taking a proper amount of a mixed water solution containing soluble phosphate and soluble salt of zirconium, wherein the molar ratio of Zr<4+> and PO43 in the mixed water solution is 0.5-2, and the ion total concentration of Zr<4+> and PO4<3-> is 0.1-5mol / L; forming a porous heteropoly acid substance by the Zr<4+> and PO4<3-> in the mixed aqueous solutions; adsorbing the heteropoly acid substance on the surface of metal oxide by using an impregnation method, or complexing the soluble salt solution of Ce and the heteropoly acid substance to form sol under the assistance of a complexing agent by using a sol gel method; and finally drying and roasting to prepare a catalyst powder. The mass fraction of metal oxide in the catalyst is 60%-95%, and the mass fraction of heteropoly acid substance is 5%-40%. The catalyst prepared by the invention has strong water thermal aging and sulfuration resistance ability, and low cost.

Description

A kind of CeO 2base SCR Catalysts and its preparation method

[technical field]

The present invention relates to SCR catalyst, particularly relate to a kind of CeO ₂base SCR Catalysts and its preparation method.

[background technology]

It is high that diesel vehicle has the thermal efficiency than gasoline car, economical good, CO ₂discharge low feature; but the feature due to diesel car engine; NOx and particle solid particulate matters such as () the dry soot C of the dissolved organic matter SOF of liquid phase and solid phase and sulfate discharge is compared with gasoline overall height; wherein NOx a kind of main polluter especially, has all formed great harm for environmental protection and health.Diesel engine is owing to being lean-combustion engine, the O in tail gas ₂concentration higher (> 6%), therefore can not as gasoline car, utilize three-way catalyst (TWC) to carry out the removal of NOx, must the purified treatment that SCR catalyst carries out NOx be installed in the after-treatment device of tail gas, for denitration.Power plant and cement plant are owing to using a large amount of coals as fuel; the NOx in the flue gas of discharge with high level for requirement and the rules of the protection that conforms, also must install SCR after-treatment device in power plant and cement plant; utilize SCR catalyst to carry out the purified treatment of NOx, for denitration.

In the last few years, V ₂o ₅-WO ₃/ TiO ₂catalyst is due to good activity, preferably heat endurance is widely used as the commercial catalyst of exhaust gas from diesel vehicle and power plant, smoke denitration of cement plant.But V is a kind of poisonous element, flow in nature, by the enrichment of biological chain, environment and human body are produced to a large amount of harm, this runs counter to the sustainable development view of mutually coordinating between environmental protection and economic development.So, without the exploitation of V catalyst, caused gradually people's attention.CeO ₂there is good oxygen mobility, there is certain redox active simultaneously, be widely used as in gasoline car three-way catalyst.Therefore, people also start to pay close attention to CeO gradually ₂application in preparation SCR catalyst.

Existing CeO ₂base SCR catalyst is mainly with CeO ₂for active component, or with CeO ₂and ZrO ₂the metal oxide forming is active component, adds and improve component, for example P on the basis of active component ₂o ₅or Nb ₂o ₅, the catalyst cupport obtaining (according to application scenarios difference, is selected to different carriers) on carrier.Above-mentioned SCR catalyst, although during NOx purified treatment in certain temperature range the conversion ratio of NOx can reach more than 80%, its anti-sulfuration, water resistant heat aging performance are not strong, have limited the use of catalyst yet.This be because: diesel oil and coal produce a large amount of high-temperature vapors and SO as fuel combustion meeting ₂, so SCR catalyst need to have certain water resistant heat ageing, the ability of anti-sulfuration.

[summary of the invention]

Technical problem to be solved by this invention is: make up above-mentioned the deficiencies in the prior art, propose a kind of CeO ₂base SCR Catalysts and its preparation method, the ability of the catalyst water resistant heat ageing making, anti-sulfuration is stronger, and cost is lower, and the conversion ratio of the NOx in simultaneous temperature operation window (250～450 ℃) is also higher, meets application demand.

Technical problem of the present invention is solved by following technical scheme:

It is a kind of,

In preferred technical scheme,

In further preferred technical scheme,

The beneficial effect that the present invention is compared with the prior art is:

CeO of the present invention ₂base SCR Catalysts and its preparation method, in the catalyst making by Zr ⁴⁺and PO ₄ ^3-according to certain mol proportion, form the heteropoly acid material of porous, this heteropoly acid material is attached to CeO by the mode of dipping or complexing ₂the surface of metal oxide.This heteropoly acid material can improve catalyst surface acidity and then reduce SO ₂at CeO ₂the adsorption and oxidation on surface, thereby the anti-curability of raising catalyst; The heteropoly acid structure of similar basic zirconium phosphate prepared by simultaneously the present invention has very high heat endurance, under hot environment also not can with CeO ₂structural interaction cause catalysqt deactivation, and then make catalyst there is very high water resistant hot property.Experimental verification, catalyst is after over cure, hydrothermal treatment consists, and the property retention of catalyst is stable, and the conversion ratio of NOx still keeps higher level.In addition, in preparation process, PO ₄ ^3-react the porous heteropoly acid material that generates stratiform with zirconates, this heteropoly acid material not only can improve the surface acidity of catalyst, and because its high-specific surface area also can increase the specific area of catalyst, from two aspects, promotes catalyst for NH ₃adsorptivity, promote catalytic efficiency.Experimental verification, the conversion ratio of the NOx in 250～450 ℃ is higher, approaches 100%.Meanwhile, catalyst n ₂selective also higher, all more than 90%.In preparation process, the material of selecting is CeO ₂or the soluble-salt of Ce, the soluble-salt of soluble phosphate and zirconium, with respect to using CeO in existing preparation process ₂, P ₂o ₅or Nb ₂o ₅, the cost of raw material reduces a lot, so the cost of catalyst prod is lower.Method for preparing catalyst of the present invention is simple, and production cost is low, is convenient to industrialization, can be widely used in NO in exhaust gas from diesel vehicle and power plant, cement plant flue gas _xdenitration process.

[accompanying drawing explanation]

Fig. 1 is the catalyst that makes in the experimental example 1 of the specific embodiment of the invention scanning electron microscope (SEM) photograph under different resolution;

Fig. 2 is the catalyst that makes in the experimental example 4 of the specific embodiment of the invention scanning electron microscope (SEM) photograph under different resolution;

Fig. 3 is the catalyst that makes in the experimental example 5 of the specific embodiment of the invention scanning electron microscope (SEM) photograph under different resolution;

Fig. 4 is the catalyst that makes in the experimental example 8 of the specific embodiment of the invention scanning electron microscope (SEM) photograph under different resolution.

[specific embodiment]

Below in conjunction with the specific embodiment and contrast accompanying drawing the present invention is described in further details.

Catalyst of the present invention, with CeO ₂for basis, Zr ⁴⁺and PO ₄ ^3-the heteropoly acid material of the porous of the stratiform forming is coated on CeO ₂surface, by heteropoly acid material assistance CeO ₂, make CeO ₂give full play to the effect of active component, provide active oxygen to participate in catalytic reduction reaction, thereby performance catalyst transforms the denitration of NOx.Simple CeO ₂for active component, because its surface acidity is very low, its denitration performance is very poor.And surface is coated with the CeO of heteropoly acid material ₂, its surface acidity is enhanced, and surface area is also increased dramatically, and therefore can effectively promote NH ₃adsorptivity, utilize NH ₃by the NO in waste gas _xsCR becomes N ₂and water, promote catalytic efficiency.Meanwhile, this heteropoly acid material can improve catalyst surface acidity and then reduce SO ₂at CeO ₂the adsorption and oxidation on surface, thereby the anti-curability of raising catalyst; The heteropoly acid structure of similar basic zirconium phosphate prepared by simultaneously the present invention has very high heat endurance, under hot environment also not can with CeO ₂structural interaction, and then make catalyst there is very high water resistant hot property.And determine by this Zr ⁴⁺and PO ₄ ^3-the porous heteropoly acid material forming is as CeO ₂auxiliary collaborative component, neither hold facile.In R&D process, also attempted SO ₄ ^2-, Nb ₂o ₅h ₂o, WO ₃or MoO ₃, but these compositions lead to the failure because of different separately reasons.For example, while using separately phosphoric acid as auxiliary element, phosphoric acid meeting and CeO ₂interact and generate cerous phosphate, cause catalysqt deactivation.Again for example, Nb ₂o ₅h ₂o during as auxiliary element, easily becomes Nb in hot environment ₂o ₅lose acidity, make the catalyst making cannot be applicable to hot environment.As considered, use phosphoric acid and Nb ₂o ₅h ₂o, phosphoric acid is difficult to and Nb ₂o ₅reaction after mixing, but be easier to and CeO ₂reaction generates cerous phosphate, causes catalysqt deactivation, still can not address this problem.And WO ₃and MoO ₃same easy and active component CeO ₂in hot environment, reaction generates cerium salt, causes catalysqt deactivation.Therefore, in the present invention, select Zr ⁴⁺and PO ₄ ^3-the porous heteropoly acid material forming is long-time research and development, after many-side test is feasible, determines and obtains.

For making heteropoly acid material and CeO ₂be attached together, heteropoly acid material and CeO ₂carry out the mixing of atomic level, use infusion process heteropoly acid material to be adsorbed on to the surface of metal oxide, or use sol-gel process, by complexing agent, the soluble-salt solution of Ce is formed to colloidal sol together with the complexing of heteropoly acid material, finally equal Kaolinite Preparation of Catalyst powders after super-dry, roasting.

In the present invention, the soluble-salt of the zirconium of use is Zr (NO ₃) ₄5H ₂o, ZrOCl ₂8H ₂o, Zr (CH ₃cO ₂) ₄, ZrCl ₄or Zr (OH) ₄.The soluble-salt of Ce is Ce (NO ₃) ₄6H ₂o, Ce (NO ₃) ₃6H ₂o, CeCl ₃7H ₂o, Ce ₂(C ₂o ₄) ₃10H ₂o or (CH ₃cO ₂) ₃ceKH ₂o; Wherein, K represents positive integer.Soluble phosphate is (NH ₄) ₂hPO ₄, or NH ₄h ₂pO ₄, or (NH ₄) ₃pO ₄, or (NH ₄) ₂hPO ₄, or APP (NH ₄, H) _n+ 2P _no _3n+1.

Concrete experimental example is set as follows to be described:

Experimental example 1: adopt infusion process preparation.

1) get a certain amount of CeO ₂account for the cerium zirconium sosoloid powder of 80wt%, the amount of choosing guarantees that the mass fraction that metal oxide accounts for the whole catalyst making is 90%.In powder, can only comprise CeO ₂, why adulterate ZrO ₂, be because doping ZrO ₂after, can improve CeO ₂stability during catalytic reduction reaction.Similarly, also can doped with Al in metal-oxide powder ₂o ₃or SiO ₂.

2) get a certain amount of (NH ₄) ₂hPO ₄and ZrOCl ₂8H ₂o, the amount of choosing guarantees PO ₄ ^3-+ Zr ⁴⁺the mass fraction of the whole catalyst making after the heteropoly acid material forming accounts for is 10%, by Zr ⁴⁺with PO ₄ ^3-1:1 is dissolved in deionized water in molar ratio, forms clear aqueous solution, the Zr in the aqueous solution ⁴⁺and PO ₄ ^3-ion concentration sum be 1mol L ^-1.

3) by dipping mode the aqueous solution is loaded on to step 1) described in cerium zirconium sosoloid powder on.

4) powder is positioned over to drying box and dries 12 hours, then smash to pieces, grind, roasting is 3 hours at 500 ℃, obtains catalyst powder.This catalyst is designated as A-1.

Figure 1 shows that the scanning electron microscope sem figure of catalyst powder A-1, Fig. 1 a and Fig. 1 b represent respectively the SEM figure under different multiples.As we know from the figure, oxide particle surface is attached with loose structure material, and this loose structure is by PO ₄ ^3-and Zr ⁴⁺the heteropoly acid material forming.Zr ⁴⁺and PO ₄ ^3-form heteropoly acid material, both molar ratio range are 0.5～2, are preferably the mol ratio of the 1:1 in this experimental example.When both mol ratios are 1, can make the heteropoly acid structure of porous for being similar to layer structure, make specific area reach largest optimization value.

Metal oxide (CeO in catalyst A-1 ₂+ ZrO ₂) mass fraction be 90%, the mass fraction of heteropoly acid material is 10%, Zr in heteropoly acid material ⁴⁺and PO ₄ ^3-mol ratio be 1.

Test the SCR performance of this catalyst.During test, the atmosphere of simulation exhaust gas from diesel vehicle and power plant, cement plant flue gas configuration gas, simulation distribution composition is O ₂(5%), NO _x(500ppm), NH ₃(500ppm), HO ₂(5%), CO ₂(20%), N ₂balance, air speed is GHSV=30000h ^{– 1}, gas flow: 1000mL/min.Before test, catalyst A-1 sample is carried out to pretreatment: with the speed of 10 ℃/min at 10%O ₂air-flow (N ₂as carrier gas) in sample is heated to 500 ℃, be incubated and be cooled to room temperature after 1 hour.During test, get catalyst 0.5ml, mix with the quartz sand of 1.5ml, pack reactor into, pass into simulation distribution and carry out catalytic reduction reaction, and regulate the temperature of course of reaction, heating rate is 10 ℃/min, from room temperature to 500 ℃.Measure the NO of reactor inlet _xcontent, NH ₃the NO of content and reactor outlet _xcontent, NH ₃content, thus corresponding NO calculated _xconversion ratio and N ₂selectively.Measure to calculate and the results are shown in Table 1.

The NO of catalyst _xconversion ratio is by formula calculate the N of catalyst ₂selectively by formula $\frac{{\left[{\mathrm{NO}}_x\right]}_{\mathrm{in}}+{\left[{\mathrm{NH}}_3\right]}_{\mathrm{in}}-{\left[{\mathrm{NO}}_x\right]}_{\mathrm{out}}-{\left[{\mathrm{NH}}_3\right]}_{\mathrm{out}}}{{\left[{\mathrm{NO}}_x\right]}_{\mathrm{in}}+{\left[{\mathrm{NH}}_3\right]}_{\mathrm{in}}}$ Calculate.

Vulcanizing treatment catalyst A-1: pack catalyst into quartz ampoule, at 1000ppmSO ₂under the atmosphere of+10% steam+air, at 400 ℃, roasting 48 hours.Then the catalyst after roasting is smashed to pieces, ground, place.The SCR performance of catalyst A-1 after test vulcanizing treatment, method of testing is same as above, and test result is in Table 1.

Hydrothermal treatment consists catalyst A-1: pack catalyst into quartz ampoule, roasting is 100 hours under 800 ℃ of air atmospheres, then smashs the catalyst after roasting, grind to pieces, places.The SCR performance of catalyst A-1 after test water heat treatment, method of testing is same as above, and test result is in Table 1.

Experimental example 2: identical with the preparation process of experimental example 1, difference is only: the difference of quality, the mass fraction of the whole catalyst that metal oxide is accounted for make is 80%, the mass fraction of the heteropoly acid material of porous is 20%.Zr in heteropoly acid material ⁴⁺and PO ₄ ^3-mol ratio be still 1.The catalyst making is designated as to A-2.

The SCR performance of detecting catalyst A-2, and vulcanizing treatment, the SCR performance after hydrothermal treatment consists.Method of testing is identical with experimental example 1, at this, does not repeat.Measuring and calculation the results are shown in Table 1.

Experimental example 3: identical with the preparation process of experimental example 1, difference is only: the difference of quality, the mass fraction of the whole catalyst that metal oxide is accounted for make is 70%, the mass fraction of the heteropoly acid material of porous is 30%.Zr in heteropoly acid material ⁴⁺and PO ₄ ^3-mol ratio be still 1.The catalyst making is designated as to A-3.

The SCR performance of detecting catalyst A-3, and vulcanizing treatment, the SCR performance after hydrothermal treatment consists.Method of testing is identical with experimental example 1, at this, does not repeat.Measuring and calculation the results are shown in Table 1.

Experimental example 4: identical with the preparation process of experimental example 1, difference is only: be added with promoter.Step 2), in, get a certain amount of (NH ₄) ₂hPO ₄, ZrOCl ₂8H ₂o and Na ₂wO ₄2H ₂o (WO ₃soluble-salt), the amount chosen guarantees PO ₄ ^3-+ Zr ⁴⁺+ MO _xthe mass fraction of the whole catalyst making after the heteropoly acid material forming accounts for is 10%, by Zr ⁴⁺with PO ₄ ^3-1:1 in molar ratio, (Zr ⁴⁺+ PO ₄ ^3-) and MO _xmol ratio be 3:1, be dissolved in deionized water, form clear aqueous solution, the Zr in the aqueous solution ⁴⁺, PO ₄ ^3-and MO _xion concentration sum be 1mol L ^-1.Add after promoter, make catalyst and be designated as A-4.

Figure 2 shows that the scanning electron microscope sem figure of catalyst powder A-4, Fig. 2 a and Fig. 2 b represent respectively the SEM figure under different multiples.As we know from the figure, oxide particle surface is attached with loose structure material, and this loose structure is Zr ⁴⁺, PO ₄ ^3-and MO _xin described mixed aqueous solution, form layered porous heteropoly acid material.Comparison diagram 2 and Fig. 1 are known, add after promoter, under the effect of promoter, cavernous structure material connects into a slice, form the porous heteropoly acid material of stratiform, thereby make the loose structure of heteropoly acid material more stable, be more conducive to improve the stability of catalyst, can further reduce in practical service environment (as thermal power plant's flue gas of high dirt) dust, sulfate etc. in the deposition of catalyst surface simultaneously.It should be noted that captax O _xexcept being the WO of this experimental example ₃also can be MoO outward, ₃or H ₂sO ₄in one or more, corresponding the, soluble-salt is H ₈n ₂o ₄w, H ₂wO ₄, MoO ₃h ₂o, H ₈n ₂o ₄mo, Na ₂moO ₄2H ₂o, Na ₂sO ₄, (NH ₄) ₂sO ₄or NH ₄hSO ₄.

The SCR performance of detecting catalyst A-4, and vulcanizing treatment, the SCR performance after hydrothermal treatment consists.Method of testing is identical with experimental example 1, at this, does not repeat.Measuring and calculation the results are shown in Table 1.

Experimental example 5: adopt sol-gal process preparation.

1) get a certain amount of Ce (NO ₃) ₄6H ₂o, metal oxide CeO in the catalyst that the amount of choosing is guaranteed finally to make ₂mass fraction be 95%.

2) get a certain amount of Zr (NO ₃) ₄5H ₂o, (NH ₄) ₂hPO ₄, deionized water is evenly mixed to get settled solution, PO in the catalyst that the amount of choosing is guaranteed finally to make ₄ ^3-+ Zr ⁴⁺the mass fraction of the heteropoly acid material forming is 5%, by Zr ⁴⁺with PO ₄ ^3-2:1 is dissolved in deionized water in molar ratio, forms clear aqueous solution, the Zr in the aqueous solution ⁴⁺and PO ₄ ^3-ion concentration sum be 1mol L ^-1.

3) by step 1) and step 2) in solution mix, add appropriate complexing agent citric acid, the gram-equivalent number of the citric acid adding is 2 times of gram-equivalent number sum of all metal ions in solution.

4) by step 3) solution at 100 ℃, stir 3h and obtain yellow foam-like gel.Gel obtains gel solid at 110 ℃ of dry 12h.

5) by gel solid 300 ℃ of heat treatments 1 hour, be warming up to 550 ℃ of roasting 3h and obtain catalyst powder.This catalyst is designated as B-1.

Figure 3 shows that the scanning electron microscope sem figure of catalyst powder B-1, Fig. 3 a and Fig. 3 b represent respectively the SEM figure under different multiples.As we know from the figure, oxide particle surface is attached with loose structure material, and this loose structure is by PO ₄ ^3-and Zr ⁴⁺the heteropoly acid material forming.

Metal oxide (CeO in catalyst B-1 ₂) mass fraction be 95%, the mass fraction of heteropoly acid material is 5%, Zr in heteropoly acid material ⁴⁺and PO ₄ ^3-mol ratio be 2.

The SCR performance of detecting catalyst B-1, and vulcanizing treatment, the SCR performance after hydrothermal treatment consists.Method of testing is identical with experimental example 1, at this, does not repeat.Measuring and calculation the results are shown in Table 1.

Experimental example 6: identical with the preparation process of experimental example 5, difference is only: the difference of quality, the mass fraction of the whole catalyst that metal oxide is accounted for make is 85%, the mass fraction of the heteropoly acid material of porous is 15%.Zr in heteropoly acid material ⁴⁺and PO ₄ ^3-mol ratio be still 2.The catalyst making is designated as to B-2.

The SCR performance of detecting catalyst B-2, and vulcanizing treatment, the SCR performance after hydrothermal treatment consists.Method of testing is identical with experimental example 1, at this, does not repeat.Measuring and calculation the results are shown in Table 1.

Experimental example 7: identical with the preparation process of experimental example 5, difference is only: the difference of quality, the mass fraction of the whole catalyst that metal oxide is accounted for make is 75%, the mass fraction of the heteropoly acid material of porous is 25%.Zr in heteropoly acid material ⁴⁺and PO ₄ ^3-mol ratio be still 2.The catalyst making is designated as to B-3.

The SCR performance of detecting catalyst B-3, and vulcanizing treatment, the SCR performance after hydrothermal treatment consists.Method of testing is identical with experimental example 1, at this, does not repeat.Measuring and calculation the results are shown in Table 1.

Experimental example 8: identical with the preparation process of experimental example 5, difference is only: be added with promoter.Step 2), in, get a certain amount of (NH ₄) ₂hPO ₄, ZrOCl ₂8H ₂o and Na ₂moO ₄2H ₂o (MoO ₃soluble-salt), the amount chosen guarantees PO ₄ ^3-+ Zr ⁴⁺+ MO _xthe mass fraction of the whole catalyst making after the heteropoly acid material forming accounts for is 5%, by Zr ⁴⁺with PO ₄ ^3-2:1 in molar ratio, (Zr ⁴⁺+ PO ₄ ^3-) and MO _xmol ratio be 2:1, be dissolved in deionized water, form clear aqueous solution, the Zr in the aqueous solution ⁴⁺, PO ₄ ^3-and MO _xion concentration sum be 1mol L ^-1.Add after promoter, make catalyst and be designated as B-4.

Figure 4 shows that the scanning electron microscope sem figure of catalyst powder B-4, Fig. 4 a and Fig. 4 b represent respectively the SEM figure under different multiples.As we know from the figure, oxide particle surface is attached with loose structure material, and this loose structure is Zr ⁴⁺, PO ₄ ^3-and MO _xin described mixed aqueous solution, form layered porous heteropoly acid material.Comparison diagram 4 and Fig. 3 are known, add after promoter, and under the effect of promoter, cavernous structure material connects into a slice, form the porous heteropoly acid material of stratiform, thereby make the loose structure of heteropoly acid material more stable, are more conducive to improve the stability of catalyst.It should be noted that captax O _xexcept being the MoO of this experimental example ₃also can be WO outward, ₃or H ₂sO ₄in one or more, corresponding the, soluble-salt is H ₈n ₂o ₄w, Na ₂wO ₄2H ₂o, H ₂wO ₄, MoO ₃h ₂o, H ₈n ₂o ₄mo, Na ₂sO ₄, (NH ₄) ₂sO ₄or NH ₄hSO ₄.

The SCR performance of detecting catalyst B-4, and vulcanizing treatment, the SCR performance of hydrothermal treatment consists.Method of testing is identical with experimental example 1, at this, does not repeat.Measuring and calculation the results are shown in Table 1.

Table 1

The B group catalyst known according to the data of table 1, the A group catalyst that infusion process makes and sol-gal process make, the NO that it is initial _xconversion ratio/N ₂selectively all higher in temperature window (250 ℃～450 ℃), can reach more than 90%, even approach 100%.And respectively organize vulcanizing treatment, after hydrothermal treatment consists and heat treatment, although its transformation efficiency and selectively decreasing, but unlikely inactivation is 0, still have and approach 70% transformation efficiency and 90% selectivity parameter, still higher, still have certain use value, effect is still better.Therefore known, each organizes the water resistant heat ageing of catalyst, and the performance of anti-sulfuration is stronger, and heat endurance is also better.

Above content is in conjunction with concrete preferred embodiment further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, make without departing from the inventive concept of the premise some substituting or obvious modification, and performance or purposes identical, all should be considered as belonging to protection scope of the present invention.

Claims (10)

1. a CeO ₂the preparation method of base SCR catalyst, is characterized in that: comprise the following steps:

1) get appropriate metal-oxide powder, described metal oxide at least comprises CeO ₂;

2) soluble-salt of getting appropriate soluble phosphate and zirconium is made mixed aqueous solution, Zr in described mixed aqueous solution ⁴⁺and PO ₄ ^3-mol ratio be 0.5～2, the Zr in described mixed aqueous solution ⁴⁺and PO ₄ ^3-ion concentration sum be 0.1～5mol/L; Described Zr ⁴⁺and PO ₄ ^3-in described mixed aqueous solution, form the heteropoly acid material of porous;

3) by step 1) in metal-oxide powder and step 2) in mixed aqueous solution adopt infusion process to mix, make described heteropoly acid material be attached to described metal oxide surface;

4) by step 3) mixture that obtains is at 80～120 ℃ of dry 1～10h that process, and then roasting 1～5 hour at 450～700 ℃, makes catalyst powder;

Wherein, in the catalyst that in the quality of described metal-oxide powder, the quality of the described aqueous solution and the described aqueous solution, the concentration of each ion makes finally to make, the mass fraction of metal oxide is 60%～95%, and the mass fraction of the heteropoly acid material of described porous is 5%～40%.

2. CeO according to claim 1 ₂the preparation method of base SCR catalyst, is characterized in that: described step 2), also comprise the step of adding promoter: in described mixed aqueous solution, add MO _xsoluble-salt, described MO _xfor WO ₃, MoO ₃, H ₂sO ₄in one or more, (Zr in mixed solution ⁴⁺+ PO ₄ ^3-) and MO _xmol ratio be 2～10, the Zr in mixed aqueous solution ⁴⁺, PO ₄ ^3-and MO _xion concentration sum be 0.1～5mol/L, by Zr ⁴⁺, PO ₄ ^3-and MO _xin described mixed aqueous solution, form layered porous heteropoly acid material.

3. CeO according to claim 1 ₂the preparation method of base SCR catalyst, is characterized in that: described step 1), metal-oxide powder also comprises ZrO ₂, Al ₂o ₃or SiO ₂in one or more.

4. a CeO ₂the preparation method of base SCR catalyst, is characterized in that: comprise the following steps:

1) get appropriate metal salt solution, described metal salt solution at least comprises the soluble-salt solution of Ce, and Ce ⁴⁺ion concentration be 0.1～5mol/L;

2) soluble-salt of getting appropriate soluble phosphate and zirconium is made mixed aqueous solution, Zr in described mixed aqueous solution ⁴⁺and PO ₄ ^3-mol ratio be 0.5～2, the Zr of described mixed aqueous solution ⁴⁺and PO ₄ ^3-ion concentration sum be 0.1～5mol/L; Described Zr ⁴⁺and PO ₄ ^3-in described mixed aqueous solution, form the heteropoly acid material of porous;

3) by step 1) in solution and step 2) in aqueous solution, add appropriate complexing agent, make described heteropoly acid material and described C _e ⁴⁺complexing, is stirred together, obtains solution; Wherein, the gram-equivalent number of complexing agent is 1～5 times of gram-equivalent number sum of all metal ions in solution;

4) by step 3) solution that obtains carries out continuous heating stirring at 100～120 ℃, and evaporate to dryness, forms gel; Gel is placed in drying box and is dried 12 hours in 80～150 ℃;

5) by step 4) the gel solid or the powder that obtain smash to pieces, grinds, and at 200～350 ℃, roasting is 0.5～3 hour, and then roasting 1～5 hour at 450～700 ℃, obtains catalyst powder;

Wherein, quality and the Ce of the soluble-salt solution of described Ce ⁴⁺the quality of concentration, the described aqueous solution and the described aqueous solution in Zr ⁴⁺, PO ₄ ^3-the concentration catalyst that makes finally to make in the mass fraction of metal oxide be 60%～95%, the mass fraction of the heteropoly acid material of described porous is 5%～40%.

5. CeO according to claim 4 ₂the preparation method of base SCR catalyst, is characterized in that: described step 2), also comprise the step of adding promoter: in described mixed aqueous solution, add MO _xsoluble-salt, described MO _xfor WO ₃, MoO ₃, H ₂sO ₄in one or more, (Zr in mixed solution ⁴⁺+ PO ₄ ^3-) and MO _xmol ratio be 2～10, by Zr ⁴⁺, PO ₄ ^3-and MO _xin described mixed aqueous solution, form layered porous heteropoly acid material.

6. CeO according to claim 4 ₂the preparation method of base SCR catalyst, is characterized in that: described step 3), complexing agent is citric acid.

7. a CeO ₂base SCR catalyst, is characterized in that: comprise metal oxide and be attached to metal oxide surface by Zr ^4+-and PO ₄ ³the heteropoly acid material of the porous forming; Wherein, described metal oxide comprises CeO ₂, the quality of metal oxide accounts for 60%～95% of whole catalyst quality; Zr in described heteropoly acid material ⁴⁺and PO ₄ ^3-mol ratio be 0.5～2, the quality of described heteropoly acid material accounts for 5%～40% of whole catalyst quality.

8. CeO according to claim 7 ₂base SCR catalyst, is characterized in that: in described heteropoly acid material, also comprise promoter, described promoter is WO ₃, MoO ₃, H ₂sO ₄in one or more.

9. CeO according to claim 7 ₂base SCR catalyst, is characterized in that: Zr in described heteropoly acid material ⁴⁺and PO ₄ ^3-mol ratio be 1:1.

10. CeO according to claim 7 ₂base SCR catalyst, is characterized in that: described metal oxide also comprises ZrO ₂, Al ₂o ₃or SiO ₂in one or more.